Conspecific tolerance in a solitary small carnivore, the Pacific marten

Holarctic martens (genus Martes) are small carnivores that are considered functionally solitary, with both resource scarcity and martens' inability to store energetic reserves posited as precluding social behavior. Interactions between martens are expected to be largely agonistic with the exception of mating and rearing of kits by adult females. Nonetheless, we documented multiple instances of conspecific tolerance by Pacific martens (M. caurina) during long-term monitoring of radio-marked animals in 2 study populations. Observations from radio-tracking and remotely triggered cam-era trap photographs suggested that pairs of martens traveled, foraged, and rested together. Presumed marten associations occurred both inter-and intrasexually and often, but not exclusively, consisted of younger (i.e., juvenile and subadult) indi-viduals. Although social interactions between martens appeared to be highly uncommon, our work nonetheless supports mounting evidence that carnivore social systems are more nuanced than presumed. We briefly explore mechanisms that could allow for plasticity in marten sociality and offer suggestions on how future efforts can continue to elucidate behav-ioral phenomena that may be rare and difficult to document.